fix typo in parameter name: should be  CSCUseGasGainCorrections
add back the packer (use version 2013) and the unpacker (should know how to read things already)
reintroduce validation pieces; start using repacked digis
don't use pre-triggers in the packer (one step back from data-like; using what's effectively been done in post-LS1 MC so far)
bypass flag added to the packer
initialize data members
Merge pull request #5034 from slava77/CMSSW_7_2_0_pre4/cscRepackRun2

Introduce repacking step in post-LS1 CSC simulation